The objective of this work is to undertake an extensive search for new quassinoids and limonoids among genera of the Simaroubaceae and Meliaceae collected in the French possessions Guyana and New Caledonia. These compounds are promising potential antineoplastic agents and demonstrate biological activity against various human parasites. As well as isolating and characterizing new compounds the project is aimed at the conversion of known biologically inactive quassinoids into compounds shown to possess activity through partial synthesis. In addition, partial synthetic studies guided by a wealth of structure-activity information should allow the preparation of biologically active quassinoid analogs.